1. Field of the Invention
The present invention relates to pressure responsive diaphragm type control valves for controlling the flow of fluid. More particularly, the valve includes an independent diaphragm which is responsive solely to the differential pressure between the controlling air pressure and the pressure of the controlled fluid that flows through the valve.
2. Description of the Prior Art
Diaphragm type control valves are used to control all kinds of fluids. Generally, the valve includes a diaphragm for supporting a valve element for movement into and out of engagement with a valve seat. A valve stem is connected to the valve element to guide the movements of the valve element into and out of engagement with the valve seat. Springs are often mounted on the valve stem to aid in opening or closing of the valve element. The movement of the diaphragm is, therefore, restricted by the mess of the valve stem, its friction, and the mass of the valve element and the bias of the spring.